634 



SEAL. 



appearance as if all the three formed a broad swim- 

 ming tail with its action upwards and downwards in 

 the vertical plane. And, as a swimming apparatus 

 the three have more varied motion than if they alto- 

 gether formed one lobe. As each of the three parts 

 has its separate articulation of bones and apparel of 

 muscles, it can of course move independently of the 

 others, and yet all the three can act in concert when- 

 ever the necessity of the animal requires such a 

 motion. From this compound structure of their 

 principal swimming apparatus, the seals have far 

 more command of themselves in the water than the 

 fishes or the Cetacca, in both of which the swimming 

 organ, though differently formed in the different 

 species, is single. In merely forward motion, the 

 advantages of the compound apparatus are not felt ; 

 and, on a stretch, both fishes and Cetacea can swim 

 faster than seals ; but the seals can sport about in 

 all directions in the water in a manner which no fish 

 or whale can ; for motion in every possible direction 

 appears to be equally easy to them. 



Their eye, which appears to be the organ of 

 sense upon which they have their chief dependence 

 when in the water, is adapted to this varied power of 

 motion. There are some peculiar modifications in 

 the general structure of the eye, which we can better 

 explain when we come to speak of the organisation 

 of the family generally ; but we may mention that 

 there is great muscular power in the iris of the eye ; 

 that the pupil expands to a broad disc when the 

 light is very faint, and that it contracts toward a 

 vertical line, as in the eye of the cat, when the light 

 falls strongly upon it. From this structure in action, 

 we may suppose that the seals chiefly ascend or 

 descend upon the fishes that form their subsistence. 

 All this section of the family, and they are the only 

 ones of the manners of which we know almost any 

 thing, are very sagacious animals, cautious in case 

 of danger, but easily tamed, and capable of play- 

 fulness and attachment, which is inferior only to that 

 of the dog. 



STENORHYNCUS. This section are distinguished by 

 the great elongation and the slenderness of the muzzle, 

 which is the foundation of the name. Their cheek 

 teeth have one prominent point in the middle of a 

 conical form and curved backwards, and there is a 

 smaller point in advance of this, and another in the 

 rear, which are also rounded in these sections, and 

 separated from the others by notches so deep that, 

 seen sideways, each has the appearance of being 

 three separate teeth. These teeth have only single 

 roots, the claws on the toes are very small, and alto- 

 gether the animals have a much more aquatic air 

 about them than the common seal. 



PKLAGIUS. This division have the muzzle elon- 

 gated, but very much enlarged toward the extremity, 

 and the profile of the forehead is very much arched. 

 The upper incisive teeth have furrows or grooves 

 across their crowns, but the under ones are simple. 

 The cheek teeth are thick and conical, with only 

 very small tubercles in front and rear of the main 

 point of the teeth. The claws on the hind feet are 

 sometimes altogether wanting. They have no exter- 

 nal concha to the ear ; and, as is the case with the 

 common seal, the females have four mammae on the 

 belly. 



STEMMATOPUS. Only one species is known as 

 belonging to this division of the family, the mitred 

 seal or crested seal of authors. Its most remarkable 



external character is a membranous appendage to the 

 upper part of the head, which is credible at the plea- 

 sure ot the animal. The cheek teeth are flat and 

 broad, and have only a single root to each. They 

 enter but a little way into the gums, and have their 

 crowns striated rather than formed into tubercles. 

 Their brain is large and well developed ; they have 

 no external ears ; their muzzle is straight and blunt 

 at the extremity ; and their tongues, like those of the 

 common seals, are short and cleft at the points. 



MACRORHINUS. This section, like the preceding 

 one, differs much from the common seal, especially in 

 the teeth. They have the fore teeth conical and 

 inclined backwards in the same way as the canines, 

 only they are smaller in size. The roots of the cheek 

 teeth are simple, and much broader than the crowns, 

 which make them have something the appearance of 

 nipples projecting from the central part of the root. 

 Some of the species are the sea elephants of authors. 



ARCTOCEPHALUS. These, as the name implies, 

 have the head formed something like that of a bear, and 

 they have on this account been called sea-bears ; but 

 the name is improper, as the animals have nothing in 

 common with bears properly so called, whether of 

 the sea or of the land. They have the head flattened, 

 the muzzle narrowed, the four middle incisors of the 

 upper jaw divided by a deep furrow in the top, and 

 the under ones with a sort of ridge in the front and 

 the rear. The cheek teeth have single roots, upon 

 which the crowns appear only as tubercles on the 

 tops of the roots ; of these there are three, the middle 

 are the largest, and the others very small. The fore 

 legs are placed far backwards : the webs of the hind 

 feet are longer than the toes, and terminate in five 

 lobes. Only one species is known. 



PLATYRHYNCUS. These have the head much arched 

 and elevated, and the muzzle flattened. Their in- 

 cisive teeth are pointed, and the hinder tubercle upon 

 the cheek teeth is wanting. In other respects they 

 very much resemble the members of the preceding 

 genus. They have been called sea-lions, which is of 

 course as incorrect as the names of land animals 

 which have been given to some of the others. 



Such are the subdivisions of the seals according 

 to the careful observations made upon them by F. 

 Cuvier, but so little is known of some of the species, 

 that no arrangement can be any thing like perfect. 

 We shall now proceed to say something of the gene- 

 ral structure. 



The seal family occupy so very peculiar a place in 

 the system of nature and occur in such numbers, 

 that a knowledge of their structure becomes a very 

 desirable, and indeed an indispensable, matter. In 

 respect of their locality and their habits, they are 

 neither sea animals nor land animals ; for they are 

 equally fitted for making both their habitation. They 

 are not amphibia in the full sense of the word, that 

 is, they are not capable of carrying on all the func- 

 tions of life equally in the land and the sea, in the 

 air and in the water. If we take this view of them, 

 they may be said to be incapable of living wholly in 

 either. They must breathe the free air, as is the 

 case with all animals which have lungs ; and although 

 it is not necessary that they should come to the land 

 to breaihe, they must rise to the surface of the water 

 always when they perform that operation. On the 

 other hand, they are quite incapable of finding their 

 food on the land, or in the air, because they are so 

 completely and exclusively formed for swimming that 



